An aberration is something that is twisted or deformed from its original or 'natural' state. It has a somewhat negative inference in English.
So, the Aberration mod is a mutating of history. Because of the negative tone of the word aberration, I never did like the name much for that mod.
Aberration and Interregnum are both mods that look at alternative history, resulting in a world of 1419 that looks different (deformed?) from the original or natural history of 1419.